1. Field of the Invention
The present invention generally relates to a locking device to be used in conjunction with a brake valve knob on a vehicle. In particular, the present invention relates to a shackle for the brake valve of a vehicle having air brakes. The shackle of the present invention is useful in preventing the inadvertent or intentional movement of the brake valve knob in a manner necessary to release the brakes.
2. Description of the Related Art
Many vehicles, and particularly large over-the-road trucks, have air brakes. As with other types of brakes, air brakes stop or hold a vehicle from movement by causing a disk or drum to apply friction to the wheels of the vehicle. However, in contrast to other types of brakes which may use mechanical, electrical, or hydraulic power to activate the brake, air brakes use air to apply the brake drum or disk. In this regard, when an air brake is activated, an air pump creates an air pressure differential in the air brake system which causes the brakes to be applied.
In most trucks, the air brakes are controlled by the operator from the cab of the vehicle. Particularly, a knob located on the dashboard of the vehicle is connected to an air valve located just behind the dashboard. Typically, pulling the knob outwardly activates the air valve and causes the brakes to be set. Pushing the knob inwardly releases the brakes.
Air brakes are particularly useful with large vehicles used in the trucking industry primarily because they permit full brake force to remain applied even when the vehicle is not in use. However, the dangers to both equipment and operators are great in the event the air brakes are inadvertently released and the truck is placed in motion. Moreover, it will be appreciated that operators of large trucks often desire to leave the engine running, with the keys in the ignition, during times when they must leave the truck unattended. Due to problems inherent in shutting off and restarting diesel engines, many drivers prefer to leave the engine running even when they desire to or must leave the vehicle unattended for a fairly long period of time, such as for example, during a time of sleep or rest from the rigors of the road. Air brakes are particularly useful during these times because they may be applied mechanically, by activating the air valve, and the brakes will be held on even though the vehicle is not in use.
The inherent problems associated with leaving an unattended vehicle running are apparent. It is not uncommon for thieves, at truck stops and the like, to unscrupulously and impermissibly enter a truck with the engine running, release the air brakes by pushing in the air brake valve knob, and drive off with the vehicle. Such losses by theft are significant when considering the cost of today's vehicles and the cargo they carry. Additionally, with the elaborate sleeping facilities available on many of today's trucks, the risk of bodily harm to a driver who might be sleeping within the truck when a thief breaks in and begins driving the truck is great in the absence of something to deter the thief from moving the vehicle.
U.S. Pat. No. 3,522,746 shows a safety device for vehicles for preventing the inadvertent movement of a control lever on the dashboard of a truck. The device incorporates a plate for preventing the lateral movement of a lever located on the dashboard. Particularly, the plate must be pivoted downwardly out of the way of the control lever to permit the lever to be moved laterally. However, the device is not adapted to prevent inward or outward movement of a knob. Moreover, the device does not deter unauthorized movement of a control lever, but only inadvertent movement.